An aromatic polycarbonate resin is excellent in, for example, transparency, mechanical property, thermal property, electrical property, and weatherability, and has been used in an optical molded article such as a light-guiding plate, a lens, or an optical fiber by taking advantage of its characteristics. A material for the optical molded article is required to have high light-guiding performance, and hence the development of a polycarbonate copolymer that improves the light-guiding performance and the improvement of the performance with various additives have been performed.
For example, the following methods have been disclosed: a method involving blending a bead-like crosslinked acrylic resin and a fluorescent whitener to reduce the luminance unevenness of the aromatic polycarbonate resin, and to make the resin excellent in color tone and surface light-emitting property (see, for example, Patent Document 1); a method involving blending an acrylic resin having a specific molecular weight, or blending a polyalkylene glycol or a fatty acid ester thereof, to improve the total light transmittance of the polycarbonate resin while maintaining its characteristics (see, for example, Patent Documents 2 and 3); a method involving setting a tin content in a polycarbonate copolymer, the copolymer to be used having a specific repeating unit, to a certain amount or less, or blending a light-diffusing agent or a specific phosphite compound as an antioxidant, to reduce the discoloration of a polycarbonate resin composition at the time of high-temperature molding while improving its flowability (see, for example, Patent Documents 4 to 6); and a method involving blending a silicone crosslinked particle and a specific phosphite compound as antioxidants to make the heat stability of the resin excellent to the extent that a large injection-molded article can be molded (see, for example, Patent Document 7).
Further, display products having larger screens and smaller thicknesses than those of conventional products such as a smart phone and a tablet PC have started to become widespread in recent years, and hence there has been a growing demand for a high-flowability material.
As a method of improving the flowability of an aromatic polycarbonate resin composition, there has been known, for example, a method involving reducing its molecular weight or such a method involving combining the composition with a polycarbonate copolymer, which is obtained by copolymerizing a polyether diol such as polytetramethylene glycol, to improve the flowability as disclosed in each of Patent Documents 4 to 6. In addition, to add a phosphite (phosphorous acid ester)-based antioxidant to the aromatic polycarbonate resin composition as disclosed in each of Patent Documents 6 and 7 has been known as a countermeasure against the deterioration or yellowing of the composition at the time of its high-temperature molding.